Explicitly install numpy in build-and-package

Averts crash while trying to install ecos, a dependency of cvxpy

Author: krivard

jenkins/build-and-package.sh

@@ -19,6 +19,7 @@ cd "${WORKSPACE}/${local_indicator}" || exit
 python -m venv env
 source env/bin/activate
 pip install --upgrade pip --retries 10 --timeout 20
+pip install numpy --retries 10 --timeout 20
 pip install ../_delphi_utils_python/. --retries 10 --timeout 20
 pip install . --retries 10 --timeout 20